CN106169682B

CN106169682B - Systems or connectors for voltage bus structures

Info

Publication number: CN106169682B
Application number: CN201610341440.2A
Authority: CN
Inventors: 克里斯托弗·J·施米特
Original assignee: Deere and Co
Current assignee: Deere and Co
Priority date: 2015-05-22
Filing date: 2016-05-20
Publication date: 2021-05-07
Anticipated expiration: 2036-05-20
Also published as: BR102016011289B1; US20160344116A1; CN106169682A; DE102016208475B4; GB201608721D0; GB2539789A; BR102016011289A2; GB2539789B; US9490555B1; DE102016208475A1

Abstract

The first bus structure includes a first outer conductive layer and a first inner conductive layer separated by a first dielectric layer. The second bus structure includes a second outer conductive layer and a second inner conductive layer separated by a second dielectric layer. The inner sleeve electrically connects the first inner conductive layer to the second inner conductive layer. An outer sleeve electrically connects the first outer conductive layer to the second outer conductive layer. A fastener extends through the inner sleeve to clamp or compress the first and second outer conductive layers toward one another.

Description

Systems or connectors for voltage bus structures

Technical Field

The present disclosure relates to a system or connector for a voltage bus structure.

Background

The voltage bus structure may be used in a vehicle, such as an electrically propelled vehicle or a hybrid vehicle propelled by an internal combustion engine, an electric motor, or both. In some applications, the voltage bus structure may be configured to operate at a peak or maximum operating voltage, a peak or maximum operating current, or both. In the context of certain vehicles, for example, high voltage operating conditions may encounter peak or maximum operating voltages of up to about 1200 Volts Direct Current (VDC). In some prior art bus structures and connectors, the switching performance and efficiency of the power semiconductor switches may be reduced if the power semiconductor switches are powered by a dc bus with increased inductance or if capacitors are required to compensate for the inductance.

In some prior art, one or more conductive connectors (e.g., conductive rectangular bus bars or stacked bus bars of opposite polarity) between different voltage bus structures may be separated to prevent short circuits and arcing, which tends to result in excessive inductance. For example, the separation of the positive and negative terminals (or traceable electrical paths in the system) may create one or more inductive loops that allow the energy of the system to be dissipated in a recirculation loop or a parasitic inductive loop. For certain vehicle or electronic applications, International Electrotechnical Commission (IEC) standards for electrical connectors may recommend or require 700 volt systems to have a spacing of about 3 millimeters, allowing clearance and heat resistance. Due to this spacing requirement, the inductance of the system increases. Inductive losses not only reduce system efficiency, but may also require an increase in the size of the conductive connection (e.g., connector) to handle the increased current generated to compensate for the inductive losses. The increased current may heat one or more connectors or high voltage buses, which tends to increase the material cost of the conductors, or else if parasitic or inductive losses are small, other materials capable of withstanding temperatures higher than the temperature of the system are required. Therefore, there is a need for a connector for a voltage bus structure that efficiently handles high voltage operating conditions.

Disclosure of Invention

According to one embodiment, a system of or for a voltage bus structure involves a first bus structure and a second bus structure. The first bus structure includes a first outer conductive layer and a first inner conductive layer separated by a first dielectric layer. The second bus structure includes a second outer conductive layer and a second inner conductive layer separated by a second dielectric layer. The inner sleeve electrically connects the first inner conductive layer to the second inner conductive layer. An outer sleeve electrically connects the first outer conductive layer to the second outer conductive layer. A fastener extends through the inner sleeve to clamp or compress the first and second outer conductive layers toward one another.

Drawings

Fig. 1 is a perspective cross-sectional view of a connector for a voltage bus structure according to the present disclosure.

Fig. 2 is a perspective sectional view of an upper portion of the connector of fig. 1.

Fig. 3 is a perspective cross-sectional view of a lower portion of the connector of fig. 1.

Fig. 4 is a top perspective view of a connector for a voltage bus structure.

Fig. 5 is a bottom perspective view of a connector for a voltage bus structure.

Fig. 6 is a side view of the connector.

Detailed Description

As used throughout this document, the system 11 will generally refer to the first bus structure 10, the second bus structure 22, the inner sleeve 74, the outer sleeve 70, its or their dielectric layers 72, the fasteners 40, and the retainers 42. The connector 55 or coaxial connector 55 portion includes an inner sleeve 74 radially spaced from an outer sleeve 70, wherein the inner sleeve 74 and outer sleeve 70 are electrically conductive or formed of a metal or alloy.

According to one embodiment, the system 11 or the connector 55 for the voltage bus structures (10, 22) relates to a first bus structure 10 and a second bus structure 22. The first bus structure 10 includes a first outer conductive layer 12 and a first inner conductive layer 14 separated by a first dielectric layer 16. A first outer aperture 32 is located in the first outer conductive layer 12; a first inner hole 34 is located in the first inner conductive layer 14. In one embodiment, first outer bore 32 has a first outer diameter and first inner bore 34 has a first inner diameter, wherein first outer bore 32 has a smaller radius or dimension than the first inner diameter. Specifically, the first outer diameter of the first outer bore 32 may be sized to match a corresponding radius of the shaft 75 of the fastener 40, while the first inner diameter may be sized to match a corresponding outer diameter of the inner sleeve 74 or the outer dielectric layer 72 thereof.

The second bus structure 22 includes a second outer conductive layer 24 and a second inner conductive layer 18 separated by a second dielectric layer 20. A second outer aperture 38 is located in the second outer conductive layer 24; a second inner hole 36 is located in the second inner conductive layer 18. In one embodiment, the second outer bore 38 has a second outer diameter and the second inner bore 36 has a second inner diameter, wherein the second outer bore 38 has a smaller radius or dimension than the second inner diameter. Specifically, the second outer diameter of the second outer bore 38 may be a dimension that is comparable to a corresponding radius of the shaft 75 of the fastener 40, wherein the second inner diameter may be a comparable dimension to receive a corresponding outer diameter of the inner sleeve 74 or the outer dielectric layer 72 thereof.

In alternative embodiments, the first bus structure 10, the second bus structure 22, or both, may include a circuit board, a printed circuit board (e.g., a double-sided circuit board). For example, the first bus structure 10 or the second bus structure 22 may use a ceramic substrate, a polymer substrate, a plastic substrate, a fiberglass substrate, or a composite substrate as the first dielectric layer 16 or the second dielectric layer 20, respectively. Further, the conductive layers (12, 14, 18, 24) may include conductive traces, microstrips, striplines, high power parallel plate transmission lines, or ground planes.

An inner sleeve 74 electrically connects the first inner conductive layer 14 to the second inner conductive layer 18. The outer sleeve 70 electrically connects the first outer conductive layer 12 to the second outer conductive layer 24. The fastener 40 extends through the inner sleeve 74 to clamp or compress the first outer conductive layer 12 and the second outer conductive layer 24 toward each other.

In one example, the inner sleeve 74 has an outer dielectric layer 72 such that the inner sleeve 74 is electrically insulated from the outer sleeve 70. In another embodiment, the inner sleeve 74 has an outer dielectric layer 72 such that the inner sleeve 74 is electrically insulated from the outer sleeve 70 and forms part of a coaxial transmission line for transmitting (simultaneously or at separate discrete points in time) a direct current signal, a low frequency alternating current signal, or both. For example, the outer sleeve 70 can be grounded while a direct current signal is transmitted in the inner sleeve 74, or while an alternating current signal is transmitted in the region between the inner sleeve 74 and the outer sleeve 70. In one example, the combination of the inner sleeve 74 and its outer dielectric layer 72, the outer sleeve 70 and its outer dielectric layer 72 comprise a coaxial connector 55 or a segment comprising a coaxial transmission line. In another example, the combination of the inner sleeve 74 and its outer dielectric layer 72, the outer sleeve 70 and its outer dielectric layer 72, the fastener 40, and the retainer 42 comprise the coaxial connector 55 or a segment comprising a coaxial transmission line.

In one configuration, one end 91 of the inner sleeve 74 electrically and mechanically contacts the first outer conductive layer 12 and an opposite end 93 of the inner sleeve 74 electrically and mechanically contacts the second outer conductive layer 24. For example, one generally annular end (91) of the inner sleeve 74 electrically and mechanically contacts a corresponding generally annular region of the first outer conductive layer 12, and an opposite generally annular end (93) of the inner sleeve 74 electrically and mechanically contacts a corresponding generally annular region of the second outer conductive layer 24.

Similarly, one end 95 of the outer sleeve 70 electrically and mechanically contacts the first inner conductive layer 14 and an opposite end 97 of the outer sleeve 70 electrically and mechanically contacts the second inner conductive layer 18. For example, one generally annular end (95) of the outer sleeve 70 electrically and mechanically contacts a respective generally annular region of the first inner conductive layer 14, and an opposite generally annular end (97) of the outer sleeve 70 electrically and mechanically contacts a respective generally annular region of the second inner conductive layer 18.

The housing 26 has an opening 99 for receiving the outer sleeve 70 or its outer dielectric layer 72. For example, the opening 99 of the housing 26 may be associated with generally cylindrical opposing walls that can be mated with or without a seal and can be sealed by a seal 51, such as an O-ring. In one embodiment, the outer sleeve 70 includes a dielectric layer 72 to form an insulative barrier relative to the housing 26 (e.g., particularly if the housing is constructed of metal and if no electrical connections or couplings are desired). The housing 26 has a first housing portion 28 secured to a second housing portion 30, and wherein one or more seals (50, 51) or gaskets provide a barrier to prevent leakage of coolant from an interior cavity 52 of the housing 26 to an exterior 56.

In one embodiment, the housing 26 may be associated with an optional inlet 101, outlet 102, or both (e.g., located in the first housing portion 28 or the second housing portion 30) for circulating fluid via a pump or via a combination of a pump, a heat sink, and a conduit or pipe (e.g., connected in series between the inlet and outlet). The inlet 101 and outlet 102 are shown in phantom to indicate that they are optional, and that they may include threaded or unthreaded connectors or tubular posts.

Fastener 40 includes a bolt and retainer 42 electrically insulated from first outer conductive layer 12 and second outer conductive layer 24 by a plurality of insulators 47. Each of the insulators 47 has a first ring portion 46 and a second ring portion 48.

A compression washer 44 is associated with one end of the fastener 40 or both ends of the fastener 40. The first outer conductive layer 12 has a raised area 60 overlying a raised dielectric portion 62; the second outer conductive layer 24 has raised areas 60 overlying raised dielectric portions 62.

In the first bus structure 10, the first outer conductive layer 12 and the first inner conductive layer 14 are capable of carrying a current, such as a direct current voltage of opposite polarity or an alternating current of different phase or different polarity. In the second bus structure 22, the second outer conductive layer 24 and the second inner conductive layer 18 are capable of carrying a current, such as a direct current voltage of opposite polarity or an alternating current of different phase or different polarity.

For example, the first outer conductive layer 12 and the second outer conductive layer 24 can carry a direct current of a first polarity, while the first inner conductive layer 14 and the second inner conductive layer 18 can carry a direct current of a second polarity, wherein the first polarity is opposite the second polarity. First outer conductive layer 12 and second outer conductive layer 24 are capable of carrying alternating current of a first polarity, and first inner conductive layer 14 and second inner conductive layer 18 are capable of carrying alternating current of a second polarity, wherein the first polarity is opposite the second polarity, wherein the alternating current has a frequency of less than about 100 kilohertz (kHz).

According to one embodiment, the connector 55 for the voltage bus structure supports a reliable and stable electrical and mechanical connection between the first bus structure 10 and the second bus structure 22. Each bus structure (10, 22) may include a bus structure capable of carrying high voltage (e.g., in the range of about 120 volts to 1200 volts dc), high current (e.g., in the range of about 10 amps to 120 amps), or both, with minimal inductance being introduced to the system 11 for a vehicle, an electric machine, an electric motor, or a generator. The connector 55 may use only one fastener 40 and associated retainer 42 (e.g., nut), which tends to minimize assembly time.

The coaxial connector 55 may be cooled by a coolant in the interior cavity 52 of the adjacent housing 26, wherein the housing 26 has an opening (e.g., a generally cylindrical opening) for receiving at least a portion (e.g., a coaxial portion) of the connector 55 for efficiently dissipating heat from the connector 55. In one embodiment, the housing 26 includes a first housing member or portion 28 and a second housing member or portion 30, wherein a generally annular region surrounding the opening 99 can be sealed by a seal 50, gasket, sealant to confine the coolant within the interior 52 of the housing 26 to prevent the coolant from leaking or otherwise spilling to the exterior 56 of the housing 26. Thus, the first bus structure 10 and the second bus structure 22 can be cooled together with the connector 55 portion passing through the housing 26, wherein the interior of the housing 26 is filled with coolant or coolant pumped through the optional ports (101, 102). Furthermore, in some embodiments, the first and second bus structures 10, 26 can rely on cooling associated with the enclosure 26 to actively cool with a circulating coolant, and any exposed surface area of the bus structures (10, 22) is passively heat diffused with ambient air without requiring additional cooling cavities or enclosures associated with the first or

second bus structures

10, 22.

In alternative embodiments, the thermal interface material may fill or be injected into any air gaps (e.g., generally annular shaped regions) that exist between the opening 99 or the outer sleeve 70 or the dielectric layer 72 thereof. For example, the thermal interface material can include thermally conductive paste, tape, or filler, where the tape or filler can include polymers, plastics, metal particles, or other filler materials having a higher thermal conductivity than air. The thermal interface material is a thermally conductive material that can be used to reduce the thermal resistance between the connector 55, the outer sleeve 70, or the dielectric layer 72 thereof, and the housing 26 (e.g., to promote heat spreading, or to promote transfer of heat in the connector 55 to the coolant in the interior 52 of the housing). In other embodiments, a portion or opening 99 of the outer sleeve 70 may have a wedge shape or a degree of conical shape, thereby forcing or extruding the thermal interface material into place between the connector 55, the outer sleeve 70, or the dielectric layer 72 thereof, and the housing 26.

Here, the connector 55 includes a coaxial bus connector defined by at least an inner sleeve 74 and an outer sleeve 70 (and an intervening dielectric layer 72). The inner and

outer sleeves

74, 70 may comprise circular, high conductivity conduits configured to connect one flat parallel plate bus structure (e.g., 10) to another flat parallel plate bus structure (e.g., 22). In one configuration, a pair of insulating sleeves 72 separate the inner and

outer sleeves

74, 70 from one another and insulate the outer sleeve 70 from the outer housing 26.

In alternative embodiments, the outer dielectric layer 72, or the outer sleeve 70, or both, may be formed with a notch or groove to retain an optional seal (e.g., an O-ring) to seal the outer sleeve 70 to the housing 26 (and separate the outer sleeve 70 from the housing 26), or to replace the dielectric layer 72.

As shown in fig. 2 and 3, each pair of ends (91 and 95, or 93 and 97) of the sleeves (70, 74) are stepped or stepped relative to one another, with the inner sleeve 74 coaxially nested or positioned within the outer sleeve 70 along axis 96. The stepped end surfaces of the sleeves (70, 74) allow each of the generally planar laminated bus structures (10, 22) to be electrically connected with the inner sleeve 74 and the outer sleeve 70.

The system 11 is held, clamped, compressed or urged together by a fastener 40 and associated retaining member 42, such as a threaded connection or other connection. The compression of the assembly system 11 is maintained by sets of compression washers 44 (e.g., Belleville washers) between the heads of the fasteners and one bus structure (10, 12) and between the retainer 42 and the other bus structure (10, 12). In one embodiment, insulation of certain components of the bus system 11 relative to the sleeves (70, 74) can be provided by a set of non-creepage (non-creepage) insulators 47 to control or adjust the reactance or inductance of the coaxial connector 55. The insulator 47 provides electrical insulation or isolation between the compression pad 44 and the first and second inner

conductive surfaces

14 and 18. For example, each insulator 47 may include a first dielectric ring portion 46 and a second dielectric ring portion 48.

In one embodiment, the thickness of the first dielectric layer 16 of the first bus structure 10 is a suitable thickness (e.g., about one-ten-thousandth of 1 inch to about one-hundred-thousandth of 1 inch, or about 0.00254 millimeters to about 0.00635 millimeters) to provide electrical insulation or isolation between the first inner conductive layer 14 and the first outer conductive layer 12. For example, in one embodiment, the thickness of the dielectric layer can be sufficient to meet IEC standards while minimizing the thickness of the first dielectric layer 16 to reduce inductance to the following levels (e.g., equal to or less than 10 nanohenries or nanohenries): no compensation capacitor is required for the first bus structure 10 providing a dc voltage for powering the one or more semiconductor switches.

In one embodiment, the thickness of the second dielectric layer 20 of the second bus structure 22 is a suitable thickness (e.g., about one-ten-thousandth of 1 inch to about one-hundred-thousandth of 1 inch, or about 0.00254 millimeters to about 0.00635 millimeters) to provide electrical insulation or isolation between the second inner conductive layer 18 and the second outer conductive layer 24. For example, in one embodiment, the thickness of the dielectric layer can be sufficient to meet IEC standards while minimizing the thickness of the second dielectric layer 20 to reduce inductance to the following levels (e.g., equal to or less than 10 nanohenries or nanohenries): no compensation capacitor is required for the second bus structure 22 providing a dc voltage to power the one or more semiconductor switches.

In one embodiment, the dielectric thickness of the dielectric layer of the inner sleeve 74 substantially meets IEC requirements or standards (e.g., meets specific creepage requirements such as from thermal expansion or differential thermal movement). The dielectric thickness of the dielectric layer 72 of the inner sleeve 74 may be selected or chosen to minimize the insulation thickness, thereby reducing the inductance of the coaxial connector 55.

The first bus structure 10 and the second bus structure 22 may carry direct current signals, alternating current signals, or both. The first bus structure 10 and the second bus structure 22 are coupled to a dc source via an electrolytic capacitor or a bank of filter capacitors, thereby reducing or minimizing the pulse current in the dc voltage supplied to the bus structures and hence to the semiconductor switching devices.

In one embodiment, the housing 26 includes a first housing portion 28 secured to a second housing portion 30 via one or more fasteners, retainers, adhesives, or clamps. In one configuration, the housing 26 is constructed of a plastic, polymer, composite, filled plastic, filled polymer, filled with filler or fiber, filler or fiber embedded in an adhesive matrix resin. The first housing portion 28 is mateable with the second housing portion 30 at a mating interface. The mating interface may have a groove or slot to receive one or more seals (50, 51) to provide a flow of coolant to cool the coaxial connectors without affecting the inductance/capacitance of the bus system 11.

In an alternative embodiment, a housing 26 composed of a metal or alloy may be used if the coaxial dielectric layer has sufficient thickness to avoid coupling between the housing 26 and the coaxial connector 55. If the interior 52 contains electronic components rather than a coolant, the housing 26, which may be composed of a metal or alloy, can be used to prevent radio frequency interference or electromagnetic interference from interfering with any circuitry of the interior 52 of the housing 26. The housing 26, which is formed of metal, can prevent electromagnetic interference from being transmitted into the housing 26 from the outside of the housing 26.

In an alternative embodiment, the dielectric layer 72 of the outer sleeve 70 may be omitted or made thinner on portions of the inner surface (e.g., the generally cylindrical interior) of the engagement opening 99 of the outer sleeve 70 to facilitate electrical or electromagnetic coupling between the metal housing 26 and the outer sleeve 70 or electrical terminals associated with the outer sleeve 70.

As shown, each outermost shim 45 appears to comprise a ring or shim. Each inner compression washer 44 is coaxially disposed inwardly from the outermost washer 45. Each respective inner compression washer 44 comprises a compression washer, such as a tempered steel or Bellville washer.

In one example, the first outer conductive layer 12 and the first inner conductive layer 14 may be composed of a metal or metal alloy including copper, nickel, and aluminum. Similarly, the second outer conductive layer 24 and the second inner conductive layer 18 may be composed of a metal or metal alloy including copper, nickel, and aluminum.

The fasteners 40 may include screws, studs, and the like. The fastener 40, retainer 42 (e.g., nut), outer washer 45, and compression washer 44 (e.g., Bellville washer), for example, may be constructed of 8.8 to 10.9 grade steel components, brass, bronze, nickel plated steel, or stainless steel. In particular, 8.8 to 10.9 grade steel components are cost effective and are substantially compatible with Copper, such as Electrical Copper (Copper) and certain Copper alloys.

In certain embodiments, each of the inner sleeve 74 and the outer sleeve 70 comprises a tube of the same metal as the metal of the conductive layer, thereby avoiding contact corrosion. The inner and

outer sleeves

74, 70 may use C11000 series or C10000 series copper. C11000 is standard electrical red copper (ETP). ETP encompasses most or all variants of the C11000 and C10000 series of copper.

In alternative embodiments, additional metals or metal alloys can be used for the fastener 40, retainer 42, and sleeve (70, 74) or other components including phosphor copper, beryllium copper, or other metals or alloys.

Here, in some embodiments, the coaxial connector 55 is circular or substantially cylindrical to facilitate a simple, reliable, and cost-effective seal 51 (e.g., to allow an O-ring to seal the housings 26 together at or near a substantially annular region).

According to certain embodiments of the present disclosure, a connector 55 having a coaxial configuration may be used without the need for a compensation capacitor or decoupling capacitor to compensate for the increased inductance of the connector 55. The design of the connector 55 is well suited for use on a bus structure (e.g., a dc bus) for driving power switching semiconductors (e.g., insulated gate bipolar diodes) of an inverter or controller for controlling an electric machine, electric motor, or generator in a run mode, a brake mode, or a generate mode without the need for decoupling capacitors to compensate for the increased inductance of the connector 55. Thus, in commercial examples of inverters, controllers, or some other electronic device using a connector 55 according to the present disclosure, the cost and weight of the decoupling capacitors can be eliminated (while maintaining acceptable inductance levels).

In certain configurations, the coaxial connector 55 of the present disclosure is well suited to control or minimize inductance to eliminate any need for oversized connectors or special metal alloys to compensate for any increased capacitance of the connector 55, which may result in size, weight, and cost reductions in commercial instances of inverters, controllers, or certain other electronic devices using the connector 55 according to the present disclosure.

Further, in accordance with the present disclosure, in one embodiment, connector 55 requires only one fastener 40 and associated retainer 42, whereas other alternative bus connectors may require multiple fasteners and additional accompanying sets of shims and insulators.

Having described one or more embodiments, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the following claims. Other embodiments of the invention may comprise any combination of features from one or more of the dependent claims, which features may be combined in any of the independent claims, either collectively or individually.

Claims

1. A system for a voltage bus structure, the system comprising:

a first bus structure comprising a first outer conductive layer and a first inner conductive layer separated by a first dielectric layer;

a second bus structure comprising a second outer conductive layer and a second inner conductive layer separated by a second dielectric layer;

an inner sleeve for electrically connecting the first outer conductive layer to the second outer conductive layer, opposite ends of the inner sleeve contacting an inner surface of the first outer conductive layer and an inner surface of the second outer conductive layer, respectively; and

an outer sleeve for electrically connecting the first inner conductive layer to the second inner conductive layer; and

a fastener extending through the inner sleeve to clamp or compress the first and second outer conductive layers toward each other, the fastener being electrically isolated from the first and second outer conductive layers.

2. The system for a voltage bus structure of claim 1 wherein the inner sleeve has a dielectric layer to electrically insulate the inner sleeve from the outer sleeve.

3. The system for a voltage bus structure of claim 1 wherein one end of the inner sleeve electrically and mechanically contacts the first outer conductive layer and an opposite end of the inner sleeve electrically and mechanically contacts the second outer conductive layer.

4. The system for a voltage bus structure of claim 1 wherein one end of the inner sleeve electrically and mechanically contacts the generally annular region of the first outer conductive layer and an opposite end of the inner sleeve electrically and mechanically contacts the generally annular region of the second outer conductive layer.

5. The system for a voltage bus structure of claim 1 wherein one end of the outer sleeve electrically and mechanically contacts the first inner conductive layer and an opposite end of the outer sleeve electrically and mechanically contacts the second inner conductive layer.

6. The system for a voltage bus structure of claim 1 wherein one end of the outer sleeve electrically and mechanically contacts the generally annular region of the first inner conductive layer and an opposite end of the outer sleeve electrically and mechanically contacts the generally annular region of the second inner conductive layer.

7. The system for a voltage bus structure of claim 1 further comprising a housing having an opening for receiving an outer sleeve.

8. The system for a voltage bus structure of claim 7 wherein the outer sleeve includes a dielectric layer to form an insulating barrier with respect to the housing.

9. The system for a voltage bus structure of claim 7 wherein the housing has a first housing member secured to a second housing member, and wherein the seal provides a barrier to prevent leakage of coolant from the interior cavity of the housing.

10. The system for a voltage bus structure of claim 1 wherein the fastener comprises a bolt and nut electrically insulated from the first and second outer conductive layers by a plurality of insulators.

11. The system for a voltage bus structure of claim 10 wherein each insulator has a first ring portion and a second ring portion.

12. The system for a voltage bus structure of claim 10 wherein the compression pad is associated with one end of the fastener or both ends of the fastener.

13. The system for a voltage bus structure of claim 10 wherein the first outer conductive layer has a raised area overlying a raised dielectric portion; wherein the second outer conductive layer has a raised area overlying the raised dielectric portion.

14. The system for a voltage bus structure of claim 1 wherein the first and second outer conductive layers are capable of carrying direct current of a first polarity and the first and second inner conductive layers are capable of carrying direct current of a second polarity, wherein the first polarity is opposite the second polarity.

15. The system for a voltage bus structure of claim 1 wherein the first and second outer conductive layers are capable of carrying alternating current of a first polarity and the first and second inner conductive layers are capable of carrying alternating current of a second polarity, wherein the first polarity is opposite the second polarity.

16. The system for a voltage bus structure of claim 1 wherein each of the first bus structure and the second bus structure includes a circuit board.